Field
The present disclosure relates to power amplifiers in radio-frequency (RF) applications.
Description of the Related Art
Power amplifiers (PAs) are widely used in networks in order to set the transmission power level of an information-bearing signal. For example, PAs are used to set the pulse emission energy of lasers in optical networks. PAs are also included in various wireless network devices—such as base stations and mobile devices—in order to set the transmission power level of a radio-frequency (RF) signal. PAs are also used in local area networks in order to enable wired and wireless connectivity of various devices.
Managing PA operation is important in a mobile device that uses a battery, because the power consumption of the PA often has a substantial impact on battery life. However, satisfying power consumption goals can be detrimental to other goals, such as linearity, which affects signal integrity and error control in data packets.
Some devices, such as wireless devices, utilize a Doherty amplifier to improve PA efficiency. In most circumstances, the Doherty amplifier has efficiency advantages over traditional single ended amplifiers.
Some advanced modulation schemes with high peak to average ratios require the amplifier to be operated several dB from their maximum saturated output power (Psat) to maintain linearity. Since a Doherty amplifier has an efficiency peak approximately 6 dB from Psat, its linear efficiency can be improved. Furthermore, the Doherty amplifier adds complexity to the PA due to an RF input splitter/phase shifter and an output combiner.